Answer :
Ok, so first we distribute, you multiply the seven into everything in the parentheses next to it. So far we have, 14a+21+3(4a-2). You distribute the three into the parentheses to get, 14a+21+12a-6. You combine the like terms to get, 26a-15. You cannot simplify it any further so the answer is 26a-15.
first distribute using distributive property
a(b+c)=ab+ac
7(2a+3)=14a+21
3(4a-2)=12a-6
add
14a+21+12a-6=26a+15
tada
26a+15
a(b+c)=ab+ac
7(2a+3)=14a+21
3(4a-2)=12a-6
add
14a+21+12a-6=26a+15
tada
26a+15
